1. Field
The present invention generally relates to the processing of semiconductor substrates, and more particularly, to methods for reducing damage to substrate layers during deposition processes.
2. Description of the Related Art
Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors and resistors) on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. As the dimensions decrease, processing of the integrated chip substrates become increasingly more challenging.
For example, in conventional substrate processing, thin layers of material are applied to the inner surfaces of substrate features prior to filling the feature with conductive material. Ideally, the thin layer would be consistent throughout the feature, while minimizing overhang (excessive material on surfaces of the opening of the feature), which can reduce the size of the feature opening, or close the opening completely (undesirably leaving an air gap trapped within the feature). As the dimensions of the integrated circuit components decrease, the aspect ratio of the height of the feature to the width of the feature increases.
Typical processes commonly used for fabricating integrated circuits having such high aspect ratio features include depositing material in a bottom of the features and re-sputtering the material to facilitate redistribution from the bottom to the sidewalls of the feature. This is done using high energy ions directed toward the substrate. Unfortunately, this method may cause damage to the underlying layers and the substrate itself, particularly at the corners, or bevel, and bottom of the feature. This damage results in significant line resistance increase and reliability degradation.
Therefore, there is a need in the art for improved methods for forming thin layers of material to the inner surfaces of high aspect ratio features.